Microelectronic devices are generally fabricated on and/or in wafers or similar substrates. In a typical fabrication process, an electroplating processor applies one or more layers of conductive materials, typically a metals, onto the substrate. The substrate is then typically subject to etching and/or polishing procedures (e.g., planarization) to remove a portion of the deposited conductive layers, to form contacts and/or conductive lines. Plating in packaging applications may be performed through a photoresist or similar type of mask. After plating, the mask may be removed, with the metal then reflowed to produce humps, redistribution layers, studs, or other interconnect features.
Many electroplating processors have a membrane separating anolyte plating liquid from a catholyte plating liquid within a bowl or vessel. In these processors, bubbles in the plating liquid may collect and stick to the bottom surface membrane. The bubbles act as an insulator, disrupting the electric field in the processor, and leading to inconsistent plating results on the work piece. Accordingly, engineering challenges remain in designing electroplating processors providing consistent plating results.